Background: Concentrations of 4 toxic metals, viz. Cd, Cu, Pb, and Zn in the soil and alfalfa samples collected from Borujerd, Iran, was determined. The capability of alfalfa to accumulate heavy metals from soils was assessed in terms of Biological Concentration Factor.Materials and Methods: The alfalfa and soil samples were collected from 20 different farms, including 13 wastewater-irrigated and seven underground-irrigated farms. After acid digestion, the samples were analyzed using atomic absorption spectrophotometer.Results: The levels of Cd, Pb, and Zn in the soils of wastewater-irrigated farms were higher than those from the groundwater-irrigated farms. With the exception of Cu, concentrations of heavy metals in the alfalfa crop were higher in wastewater-irrigated farms compared to well water. Also, in the case of BCF, both Cd and Cu values decreased with increasing metal concentration in soil. The order of BCF of heavy metals in alfalfa was in order of Cu>Cd>Zn>Pb in well water-irrigated and Zn>Cd>Cu>Pb in wastewater –irrigated samples.Discussion and Conclusions: The findings remarked that the levels of Cu, Cd, and Pb in alfalfa were exceeding the permissible levels suggested by the Joint FAO/WHO Expert Committee on Food Additives. These outcomes propose that the consumption of alfalfa plants is potentially threatening both animal and human health.